This invention relates to attraction of cells by chemicals.
Cells may be attracted to a chemical signal called a chemoattractant. For example, white blood cells localize in body tissue where trauma has occurred as a result of attraction by chemicals secreted by the tissue surrounding the trauma.
It may be desirable to investigate the inflammatory response triggered by a substance, for example to evaluate the allergenic effect of ingredients in a cosmetic designed to be administered to the skin repeatedly over long periods. Currently, one way to conduct such tests is to inject the substance subcutaneously into a mammal, e.g. a rabbit, and then to determine the degree of inflammatory response at the injection site. One particular test involves injecting the substance into rabbit eyes.
Apart from injection, a chemoattractant chemical may be evaluated using a device which releases the chemical and collects cells attracted by it. Such devices permit tests to be performed in vivo or in vitro and include inert materials such as pith, agar, collagen or polyurethane sponges into which the chemical of interest is impregnated. After insertion into living tissue or, after an in vitro experiment, the cells which accumulate in the materials can be extracted and examined.
Ford-Hutchison et al. 1978 (Journal of Pharmalogical Methods 1:3) discloses inert porous polyurethane sponges implanted subdermally into rats. These sponges were impregnated with substances such as latex, Zymosan A, Yeast or heat-killed bacteria. Non-impregnated sponges gave mild inflammatory responses, whereas sponges containing one of the above substances attracted specific cell types. These cells were collected in the sponge and their number could be estimated by squeezing liquid from the sponge.